Multiple position seam indexer

ABSTRACT

An indexer for turning a can on which the seam has not been fully welded so that the welding current goes through two or three positions on the surface of the electrode as successive can seams are turned to these positions by the indexer. The electrode erodes in definite patterns. This prolongs electrode life.

@EQ States Patent [1 1 [111 3,769,846 Aschherger Nov. 6, 1973 [54]MULTIPLE POSITION SEAM INDEXER 3,544,753 12/1970 Aschberger 219/64 [75]Inventor: Anton A. Aschberger, Oak Lawn, Ill.

[73'] Assignee: Continental Can Company, Inc., r m ry E ne Char1eS J.Myhre New York, NY. Assistant Examiner-Wesley S. Ratliff, Jr.Att0rneyAmericus Mitchell, Joseph E. Kerwin and [22] Flled' May 1971William A. Dittmann [21] Appl. No.: 142,958

Related US. Application Data [62] Division of Ser. No. 848,808, Aug. 11,1969, Pat. No. [57] ABSTRACT An indexer for turning a can on which theseam has not [52] [1.8. CI. 74/23, 219/64 b n fully welded so that thewelding current goes [51] Int. Cl. F1611 21/00 through two or threepositions on the surface of the 1 Field 01 Search 219/64 electrode assuccessive can seams are turned to these positions by the indexer. Theelectrode erodes in defi- [56] References Cited nite patterns. Thisprolongs electrode life.

UNITED STATES PATENTS 3,654,810 4/1972 Aschberger 74/54 5 Claims, 6Drawing Figures umllh lu u PMENTEDuuv sum v 3,769,846

- SHEET 10F 2 v CAN FORMING CAN WELDING STATION STATION 3;: 2 HORN I,-\\3 9 il, z

. INDEXER ELECTRODE W V\ kfik INVENTOR MULTIPLE POSITION SEAM INDEXERThis case is a division of co-pending application Ser. No. 848,808,filed Aug. 11, 1969, now US. Pat. No. 3,617,679, in the name of Anton A.Aschberger, entitled Can Body Making Method, and assigned to the sameassignee as this invention.

My invention is drawn to a can weld indexer and particularly to amachine for turning successive can seams to various predeterminedpositions before welding the seams.

Can seams are welded usually at a certain spot on the welding electrodesin most machines in use today. The electrode contacts the can seam atapproximately the same spot time after time and a furrow having a rathersharp edge is formed in the electrode. Since can blanks are of somewhatdifferent size and consistency, the can seam is not presented to theelectrode at exactly the same point each time. This results in differentpressures and different electrical currents at different parts of theseam. High electric current concentration at various points may causeuneven heating and a burn-through and a leaky can under pressure. Forthese reasons, electrodes used in can seam welding are replaced fairlyoften.

The dual problems of electrode pitting or grooving and production ofleaky cans are of long-standing in the can welding art.

It is a primary object of this invention to present can seams to anelectrode at the same point or points in each of successive weldingcycles.

-It is another object of this invention to spread electrode erosion andpitting at two or more points on the surface of the electrode. Thenumber of points depends on electrode width.

It is another object of this invention to avoid burnthrough of canwalls.

It is a final object of this invention to weld successive cans withoutburn-through.

Other objects and advantages will become apparent from the followingdescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a diagrammatic sketch of the sequence of operations of myinvention.

FIG. 2 is a sectional view of an unwelded formed can body blank takenalong Line 2-2 of FIG. 1.

FIG. 3 is a side view of an embodiment of my invention.

F IG. 4 is a diagrammatic sketch of the stages of the pusher element ofthe two position indexer embodiment.

FIG. 5 is a side view of the three position indexer.

FIG. 6 is a diagrammatic sketch of the stages of the pusher element ofthe three position indexer.

Briefly, my indexer accurately concentrates the electrode wear tosections on the face of a welding electrode by moving the unwelded sideseam of successive cans to two or more precise positions on the face ofthe electrode. In this way, grooves are accurately worn into the face ofthe electrode and the electrode does not produce leaky cans for a longtime. In order to do this, an elongated pusher element moveshorizontally to catch the lip of the elongated element against the wingedge of the formed can and rotate the can a certain amount on themandrel to present the can weld seam to certain spots on the electrodes.The welding electrodes are now pressed against the can, and as the canmoves past the electrodes, the side seam of the can is welded. Theelongated element is moved by rotating eccentric cams.

Referring now more particularly to FIGS. 1 to 6, a description of theembodiments of my invention follows:

The improvement of my invention is to precisely locate can seams in oneor more positions in relation to the electrode.

The generalized diagrammatic illustration of a section of a can bodyforming machine is shown in FIG. 1 wherein a wing forming station 1bends the can blank 2 down around a mandrel 3 to form an overlappingwing 4 of the can at the bottom. After the can has been formed aroundthe mandrel, it is moved along to a can weld station where it is welded.A variety of operations may be performed between the wing formingstation 1 and the can welding station 5. The indexer 6 which is thesubject of this invention, is located in the space between the wingforrning station and the can welding station. The outer portion 4 of theoverlapped section of the formed can sticks out a bit (FIG. 2). As it isinitially positioned on the can welding station, the can overlap sectiondoes not press against the mandrel 3. The indexer lip 7 rotates the cana predetermined amount on the mandrel and the amount of movement isusually very small. The can seam is now precisely located by the indexerand the can may now move at a moderately rapid pace between the hornmandrel 3 and the welding electrode mandrel wheel 8 to weld the canseam. As seen in FIG. 2, the outside overlapped can body edge pressesagainst the welding electrode 8 and the current coming from theelectrode 9 is to some extent concentrated at the point 10. This causesthe electrode 8 to erode and pit along the line of the can body blankedge 11. Since the successive can body blanks are presented to the canwelding station with the same orientation, one or more grooves is wornin the, electrode fairly rapidly at the point of concentration.

When a succession of cans has been formed on the mandrel, the overlap ofeach of the various cans is not always exactly the same dimensions.Because of this fact, when the edges forming the can overlap are pressedtogether, a grossly unequal pressure is applied across the overlap. Theoverlapped parts which are pressed into contact with each other mostfirmly conduct electricity most readily. The heating caused by theelectric current tends to be concentrated in the area that is mostfirmly pressed together. A large welding current passing through a smallsection of the can body overlap may burn longitudinal fissures throughthe can body. When pressure is applied inside such a can, the can isfound to be leaky.

When can seams are presented to an electrode with the same orientationtime after time, the heating of the can seam is concentrated at one spoton the electrode. Electrode erosion at the one spot is rapid and in arelatively short time, an unacceptable number of the cans produced leakalong the weld line.

In order to avoid the detrimental results set forth in the paragraphsabove, my indexer moves the can body to a predetermined different pointeach time a new can passes the indexing station. By moving the can bodyseam to two or three predetermined points across the face of anelectrode, successive can bodies are welded without moving the can bodyto the point of contact with the can seam to the electrode. Theelectrode/cam seam position is previously determined and certain areason the face of the electrode are worn. By wearing only certain areas andprecisely orienting the can seam with regard to these areas, time after.time, satisfactory welds are produced over a long period of time.

The two position embodiment of my invention shown in FIG. 3 has avertically elongated member 12 adapted to reciprocate to and fro as eachcan is presented to the can indexing station. This member 12 has apushing element 7. The pusher element is made of a fairly hard materialto avoid wear and to present the can lip to a predetermined place eachtime. The pusher element 7 presses against the edge of the can bodyblank as indicated above and moves the can body blank wing and edge apredetermined distance to the pedetermined position in regard to theelectrode. The can is thus turned on the mandrel.

Underneath the vertically elongated member 12 is a trunnion element 13which may be mounted to slide on two rods 14,15 shown one behind theother in FIG. 3. The vertical member 12 is pivotally connected to anupper connecting link 16 which connects the upper end of the member to afirst eccentric cam 17. The cam 17 is pinned to an upper shaft 18 (FIG.3) extending through a rotary motion transmitting means, such as a gear19 mounted inside the gear box or gear mounting means 20. This gearrotates another gear 21 below it to operate a second eccentric 22 whichis thus synchronized with the first eccentric. The upper gear 19 may beconnected to the lower gear through idler gear 23. The two eccentriccams 17,22 control the relative movement of the upper and lower portions24,25 of the vertical member through their respective link means 16,26.The movement of the pusher member lip 7 is thus controlled by therelative movement of the cam as described above.

In order for the pusher element to be moved a varying distance eachconsecutive time so as to place the can seam at one of two or threespots on the electrode, the first or upper eccentric turns through a 180cycle each time a can passes in frontof the pusher element. During thesame time interval that the upper cam turns through a 180 cycle, thelower cam turns through part of a 180 cycle.

In the two position embodiment of FIG. 3, each half rotation of theupper cam 17 causes a quarter rotation of the lower cam 22.

"This means that the upper eccentric cam has only half as many teeth onits keyed gear 19 as the lower eccentric cam has on its correspondinggear 21. An idler gear is located between these gears to allow the camgears to be spaced and provide motion reversal between the cammed gears.This gear is not essential to the operation. As shown in FIG. 3, theupper cam is turned so that the crank pin 26 is at its most rearwardposition. At this point, the crank pin 27 of the lower cam is at thedown position. This position corresponds to the position 2-4 shown inFIG. 4.

With the crank starting in the position shown in FIG. 3, the sequence ofmotion of the elongated element is as shown in FIG. 4. Namely, startingat the point 22, the lower cam is in the lower position, the uppereccentric is in the maximum rearward position. At this state, a can withits wing is inserted so that its wing hangs down just in front on thepusher lip 7. Pusher lip 7 is at a maximum rearward position. Next, thecams turn and the elongated element 12 moves forward to assume theposition shown as 3,3,3. At this stage, the pusher lip is at a certainpoint of alignment with the electrode. Now, the upper cam which is atits maximum forward position, begins the next of its rotation. Theelongated element assumes the position shown along the line 4-4. At thisstage, the upper crank pin 26 is at its most rearward position while thelower crank pin 27 is at its most upper position or half-way betweenfront and rear. The lip 11 is at its rearmost position. Now, a new canwith its wing comes in front of the lip. The upper pin 26 rotates to theforward position and the lower crank pin 27 comes to the forwardposition. At this stage, the lip and elongated member are along the line1l. The wing and can have now rotated into a position where the wing andcan seam will strike the rotating electrode along the line 1 1. Thisline is a small distance from the line 33 so that the can seam ofsuccessive cans are pressed against two different locations on therotating electrode. the rotating electrode will have two wear spotsalong its circumference. For this reason, the electrode will last two ormore times longer than an electrode without the indexer.

In brief, each time the upper eccentric cam is in its rearmost position,the lower eccentric cam is at the top or bottom of its cycle. When theupper cam is at its forwardmost position, the lower cam is at the frontor rear position of its cycle. In this way, when the upper cam is at itsrearmost position, the pusher lip is retracted. When the upper cam is atits forward position, the pusher lip is at one of two forwardmostpositions.

My embodiment of a three position indexer is shown in FIGS. 5 and 6. Inthis embodiment, the upper gear 28 mounted on the drive shaft 29 of thefirst cam 30 has 20 teeth around its perimeter, whereas the gear 31mounted on the drive shaft 32 of the second cam 33 has 60 teeth aroundits perimeter. In this case, for each half rotation of the upper gear28, there is a non-sixth rotation of the lower gear 31.

In this embodiment, the lip pressed against the wing of the unwelded canand moves it to one of three forward positions on the electrode so thatelectrode wear occurs at one of three positions across the electrode.When the three position indexer is in the position shown in FIG. 5, thelip 7 and elongated member 12 is in the position of 2,2. in FIG. 6. Thatis to say, the lower crank pin 34 is at its median lowermost positionand the upper crank pin 35 is in its most rearward position. FIG. 6 likeFIG. 4 is to a larger scale than its corresponding FIG. 5 in order toemphasize the lengths and distances involved. As the upper crank or camturns to its most forward position, the lower crank turns onesixths of arevolution. This moves the lower crank to position 3 and the upper crankto its most forward position. Now, the lip and elongated member liealong the line 3-3 and the lip is at its most forward position. Theupper crank now turns half a revolution, withdrawing the upper part ofthe member to its most rearward position and the lower crank movesone-sixth of a revolution. This will place the lip and elongated memberalong the line 4-4. This sequence of events continues so long as thecranks'are rotated. The indexer drive is synchronized with the canforming mechanism so that each time the indexer returns to its rearwardposition, a can with its wing is inserted in the area immediately infront of the lip. Thus, as the lip moves forward, it will position thecan wing edge at one of three positions across the face of theelectrode.

The indexer drive and the can forming apparatus are synchronized so thatthe pusher lip is always at its rearward position when the can wing isadvanced to oppose it on the horn.

It is readily appreciated that within the limits of practicality, anynumber of positions may be indexed across the face of an electrode. Thenumber of positions is limited by the lateral area of the electrode, andthe width of the can seam. The seam width across the usual can is about0.04 inch.

A principal aTivaiifige of my seam welding indexer is that one or moreconsistent paths are worn across the electrode, giving a longerelectrode life and causing more complete can seam welding.

The foregoing is a description of an illustrative embodiment of theinvention, and it is applicants intention in the appended claims tocover all forms which fall within the disclosure of the invention.

What is claimed is:

l. A multiple position can welding indexer comprising:

a mounting means for mounting at least two parallel shafts for rotation;

at least two spaced shafts extending through said mounting means;

a first rotary motion transmitting means keyed to a second shaft forbeing rotated by said first rotary motion transmitting means;

said second rotary motion transmitting means being in size an integralmultiple of said first rotary motion transmitting means whereby for eachrevolution of said second shaft, said first shaft revolves an integralnumber of at least two times;

a first and a second eccentric cam keyed to each of said first andsecond shafts in such a manner that the position of said first cam meansis at its rearmost position at the same time that said second cam meansis at its intermediate position;

an elongated member spaced from said first and second shafts, and havinga pusher lip; and

first and second link means pivotally connected to first and secondspaced points of said elongated member and being actuated by said firstand second eccentric cam respectively at the other end and movable inresponse to the rotation of each said eccentric cam and shaft wherebysaid lip moves between predetermined positions of forward and rearwardtraverse.

2. A multiple portion can welding indexer as set forth in claim 1 inwhich:

a driving means is attached to one of said shafts for rotating saidshafts in synchronism with a wing forming drive means whereby for eachwing forming cycle, the can welding indexer goes through a completecycle.

3. A multiple position can welding indexer as set forth in claim 1 inwhich:

said first and second rotary motion transmitting means are gears; and

said second rotary motion transmitting means has teeth the number ofwhich are an integral multiple of the number of teeth of said firstrotary motion transmitting means.

4. A multiple position can welding indexer as set forth in claim 1 inwhich:

said second rotary motion transmitting means is double the size of saidfirst rotary motion transmitting means whereby for each revolution ofsaid second shaft, said first shaft revolves two times; and

the rotary motion transmitting means are placed in relation to eachother so that the position of said first link means is at its mostrearward when said second link means is in its intermediate position.

5. A multiple position can welding indexer as set forth in claim 1 inwhich:

said second rotary motion transmitting means is treble the size of saidfirst rotary motion transmitting means whereby for each revolution ofsaid second shaft, said first shaft revolves three times; and

said first and second rotary motion transmitting means being connectedin such a position that when said first link means is at its mostrearward position, said second link means is in its intermediateposition and said lip moves between three predetermined forwardpositions and three predetermined rearward positions.

1. A multiple position can welding indexer comprising: a mounting means for mounting at least two parallel shafts for rotation; at least two spaced shafts extending through said mounting means; a first rotary motion transmitting means keyed to a second shaft for being rotated by said first rotary motion transmitting means; said second rotary motion transmitting means being in size an integral multiple of sAid first rotary motion transmitting means whereby for each revolution of said second shaft, said first shaft revolves an integral number of at least two times; a first and a second eccentric cam keyed to each of said first and second shafts in such a manner that the position of said first cam means is at its rearmost position at the same time that said second cam means is at its intermediate position; an elongated member spaced from said first and second shafts, and having a pusher lip; and first and second link means pivotally connected to first and second spaced points of said elongated member and being actuated by said first and second eccentric cam respectively at the other end and movable in response to the rotation of each said eccentric cam and shaft whereby said lip moves between predetermined positions of forward and rearward traverse.
 2. A multiple portion can welding indexer as set forth in claim 1 in which: a driving means is attached to one of said shafts for rotating said shafts in synchronism with a wing forming drive means whereby for each wing forming cycle, the can welding indexer goes through a complete cycle.
 3. A multiple position can welding indexer as set forth in claim 1 in which: said first and second rotary motion transmitting means are gears; and said second rotary motion transmitting means has teeth the number of which are an integral multiple of the number of teeth of said first rotary motion transmitting means.
 4. A multiple position can welding indexer as set forth in claim 1 in which: said second rotary motion transmitting means is double the size of said first rotary motion transmitting means whereby for each revolution of said second shaft, said first shaft revolves two times; and the rotary motion transmitting means are placed in relation to each other so that the position of said first link means is at its most rearward when said second link means is in its intermediate position.
 5. A multiple position can welding indexer as set forth in claim 1 in which: said second rotary motion transmitting means is treble the size of said first rotary motion transmitting means whereby for each revolution of said second shaft, said first shaft revolves three times; and said first and second rotary motion transmitting means being connected in such a position that when said first link means is at its most rearward position, said second link means is in its intermediate position and said lip moves between three predetermined forward positions and three predetermined rearward positions. 